Atlantic croaker, Micropogonias undulatus (Linnaeus, 1766) Although Atlantic croaker occur throughout much of Florida, they are seldom found south of Tampa Bay on the gulf coast or south of the Indian River Lagoon on the Atlantic coast. Lankford et al. (1999) found that the genetic population structure of Atlantic croaker in U.S coastal waters consisted of separate, weakly differentiated stocks in the Atlantic and Gulf of Mexico. Atlantic croaker are medium-sized members of the drum family. Most individuals are less than 14 inches long when caught. Young Atlantic croaker use estuaries as nursery and feeding grounds (Arnoldi et al. 1974), but by the time they are 3 4 inches long, they begin to migrate into nearshore waters (Parker 1971). Adults are often found over mud bottoms in areas of low to moderate salinity. The maximum reported age is 8 years (Barger 1985; Barbieri et al. 1994). Atlantic croaker reach 7 10 inches at age 1 and 12 17 inches at age 5 (Table 1; Barger 1985; Ross 1988; Barbieri et al.1994). They mature at the end of their first or second year, when they are 6 to 10 inches in total length (White and Chittenden 1977). Spawning occurs over the nearshore continental shelf during the late fall and winter. Table 1. Von Bertalanffy growth parameters and length-weight relations for Atlantic croaker Inches TL = L (1-e -K(age-t 0 ) ) K L (inches TL) t0 (years) Source Combined sexes, north Gulf of 0.27 16.5-1.405 Barger (1985) Mexico Combined sexes, North Carolina 0.20 25.4-0.60 Ross (1988) Combined Sexes, Chesapeake Bay 0.36 12.3-3.26 Barbieri et al. (1994) Combined sexes, Atlantic coast 0.214 16.26-2.35 ASMFC (2010) Weight in lbs = a (inches TL) b a b Source Combined sexes, north Gulf of 0.000295 3.134 Barger (1985) Mexico Combined sexes, North Carolina 0.000244 3.23 Ross (1988) Combined sexes, Chesapeake Bay 0.000230 3.30 Barbieri et al. (1994) Combined sexes, Atlantic coast 0.0000073 3.14 ASMFC (2010) The major prey of young-of-the-year Atlantic croaker are polychaetes, copepods, and mysids; adult Atlantic croaker primarily feed on crustaceans, molluscs, and fish (Mercer 1989). Predators of Atlantic croaker include larger piscivorous species such as striped bass, southern flounder, sharks, spotted seatrout, Atlantic croaker, red drum, sheepshead, bluefish, and weakfish (Levine 1980; Mercer 1989). Total statewide landings of croaker in 2015 were 262,302 pounds; the recreational fishery made 84% of the statewide landings. Landings were greater on the Atlantic coast, where about 91% of the statewide landings. In 2015, reported commercial landings were highest in Duval County on the Atlantic coast (Fig. 1a). Estimated recreational landings were highest among Florida Fish and Wildl. Conserv. Comm., FWRI (2016) ATLANTIC CROAKER - 46
Nassau through Brevard Counties on the Atlantic coast (Fig. 1b). Total annual landings of Atlantic croaker declined sharply during the late 1980s, increased slightly during 1991 1995, and declined again during 1996 1997. Total annual landings of Atlantic croaker increased slightly but remained at low levels. The 2015 total landings were about 28% lower than the average landings in the previous five years (2010 2014) and were 62% lower than the 1982 2014 historical average landings (Fig. 2). On the Atlantic coast, the standardized commercial catch rate increased during 1992 2000, showed a sharp decline in 2001, and has since shown cyclic catch rate patterns in 2002-2005, 2006-2009, and 2010-2015 (Fig. 3a). On the gulf coast, commercial catch rates have been variable and without a long-term trend from 1992-2006, and has shown an increasing trend from 2007-2010 followed by a steep decreasing trend through 2014, however catch rates rebounded in 2015 (Fig. 3b). Since 1993, recreational standardized catch rates have also shown cyclic patterns on the Atlantic coast, with lows occurring in 2003, 2010, and 2014-2015 (Fig. 3c). On the gulf coast, catch rates display a variable declining trend from 1991 through 2005, followed by a peak in 2011-2012, returning to historic lows in 2015 (Fig. 3d). Indices of abundance for young-of-the-year (YOY) Atlantic croaker were also cyclical with highs in 2001, 2005, and 2010-2011. Recent years indices have remained low (Fig. 4a). On the gulf coast, YOY indices were relatively low throughout the time series with evidenced strong year classes in 2004-2005, 2010-2012, and 2014 (Fig. 4b). Post-YOY indices of Atlantic croaker show peaks in 1999, 2003, 2005, 2010-2011, and 2015 (Fig 4c). On the gulf coast, post-yoy indices were low for the majority of years between 1997 and 2015 with a steep increase in 2011-2012 (Fig. 4d). The proportion of Atlantic croaker captured with gross external abnormalities was the highest in 2006 on the Atlantic coast, and proportions have no trend on the Gulf coast (Figs. 5a and 5b). Parasites occurred on the Atlantic coast during 2015 (Fig. 5c). There have been no specific stock assessments developed for Atlantic croaker in Florida. Simple equilibrium yield-per-recruit analyses for Atlantic croaker in Chesapeake Bay showed that they had a high biological capacity to resist growth overfishing (Kline 1993, Barbieri et al. 1997). While it was estimated that current fishing rates had reduced stock biomass by two-thirds in Chesapeake Bay, nothing is known about how this had affected the reproductive capacity of the stock. There have been three inter-state assessments of the Atlantic coast stock on the Atlantic coast (Hightower et al. 2000; ASMFC 2005, 2010) and a new benchmark assessment is currently underway. The 2010 stock assessment indicated that F declined substantially during 1988 1992, and retrospective analysis of the model showed that estimates of F decreased as more years of data were used. Recruitment (age-1 abundance) has been variable but generally increasing over the time series. Absolute estimates of SSB were unavailable because of model uncertainty; however, the general trend in SSB from the model was considered reliable due to support from the data. SSB showed a nearly consistent increasing trend since 1998 and the agestructure of the population has been expanding since the late 1980s. The resource was not experiencing overfishing; however, model estimates of SSB were too uncertain to be used to precisely determine overfished stock status. Florida Fish and Wildl. Conserv. Comm., FWRI (2016) ATLANTIC CROAKER - 47
a. Commercial landings (pounds) b. Recreational landings (numbers) Figure 1 (a)-(b). Geographic distribution of Atlantic croaker landed during 2015. (a) Commercial landings (pounds) by county; (b) Recreational landings (numbers of fish) by region. Figure 2. Total annual landings (pounds) of Atlantic croaker on the Atlantic and gulf coasts of Florida, 1982 2015. Florida Fish and Wildl. Conserv. Comm., FWRI (2016) ATLANTIC CROAKER - 48
a. Atlantic coast YOY b. Gulf coast YOY c. Atlantic coast post-yoy d. Gulf coast post-yoy Figure 4 (a)-(d). Proportion of fishery-independent-monitoring sets that captured Atlantic croaker from 1997-2015. Young-of-the-year (Y-O-Y): (a) Atlantic Coast; (b) Gulf Coast. Post-Y-O-Y (c) Atlantic Coast; (d) Gulf Coast. Florida Fish and Wildl. Conserv. Comm., FWRI (2016) ATLANTIC CROAKER - 49
a. Atlantic coast, proportion of total collected b. Gulf coast, proportion of total collected c. Atlantic coast, percentage of abnormality by type d. Gulf coast, percentage of abnormality by type No Available Data Figure 5 (a)-(d). Gross external abnormalities of Atlantic croaker > 75mm collected in fishery-independent-monitoring sets, 1999-2015. Breakdown of gross external abnormalities by coast: (a) Atlantic coast; (b) Gulf coast. Percentage of abnormalities observed by type: (c) Atlantic coast; (d) Gulf coast. Florida Fish and Wildl. Conserv. Comm., FWRI (2016) ATLANTIC CROAKER - 50